Heat exchanger and air-conditioning apparatus

Abstract

A heat exchanger includes flat cross-sectional shaped heat transfer tubes arranged with gaps between flat surfaces of the flat heat transfer tubes facing each other, and each having a flow passage in a vertical direction, and corrugated fins disposed between the flat surfaces facing each other. The corrugated fins each include an end portion in a direction in which air flows, and protruding from end portions of the flat surfaces, a drain hole provided adjacent to central regions of the flat surfaces in the direction in which the air flows, first louvers located upstream of the drain hole, and each including a slit and a slat that is inclined in the vertical direction, and second louvers located downstream of the drain hole, and each including a slit and a slat that is inclined in the vertical direction.

The invention claimed is: 
     
       1. A heat exchanger, comprising:
 a plurality of flat heat transfer tubes each having a flat shape in cross section, the plurality of flat heat transfer tubes being arranged with gaps between flat surfaces of the plurality of flat heat transfer tubes facing each other, the plurality of flat heat transfer tubes each having a flow passage extending through a corresponding one of the plurality of flat heat transfer tubes in a vertical direction; and 
 a plurality of corrugated fins each bent in a zigzag shape in the vertical direction and disposed between the flat surfaces facing each other, 
 the plurality of corrugated fins each having 
 an end portion at an upstream end in a first direction in which air flows to pass through the plurality of corrugated fins, the end portion protruding from end portions of the flat surfaces of the plurality of flat heat transfer tubes, 
 a drain hole provided adjacent to central regions of the flat surfaces of the plurality of flat heat transfer tubes in the first direction, 
 a plurality of first louvers located upstream of the drain hole in the first direction, the plurality of first louvers each including a slit and a slat that is inclined in the vertical direction and that causes the air to flow through the slit, and 
 a plurality of second louvers located downstream of the drain hole in the first direction, the plurality of second louvers each including a slit and a slat that is inclined in the vertical direction and that causes the air to flow through the slit, 
 a width of the drain hole in the first direction in which the air flows being greater than or equal to one-half of a maximum interval of the zigzag shape in the vertical direction, a length of the drain hole in a second direction in which the plurality of flat heat transfer tubes are arranged being greater than or equal to one-half of a length of each of the plurality of corrugated fins in the second direction in which the plurality of flat heat transfer tubes are arranged, the second direction being orthogonal to the first direction, 
 the drain hole being shaped in such a manner that a width of the drain hole gradually decreases from both ends toward a center in the second direction. 
 
     
     
       2. The heat exchanger of  claim 1 , wherein the plurality of corrugated fins each further include water guiding projections on the end portion of a corresponding one of the plurality of corrugated fins, the water guiding projections being each inclined toward a corresponding one of the plurality of flat heat transfer tubes in such a manner that a gap between the water guiding projections increases from upstream ends to downstream ends of the water guiding projections in the first direction. 
     
     
       3. The heat exchanger of  claim 1 , wherein the slats of each of the plurality of first louvers each have an upstream end in the first direction, the upstream end being inclined upward, and the slats of each of the plurality of second louvers each have a downstream end in the first direction, the downstream end being inclined upward. 
     
     
       4. The heat exchanger of  claim 1 , further comprising an additional plurality of flat heat transfer tubes arranged in the first direction,
 wherein the plurality of corrugated fins each include the drain hole, the plurality of first louvers, and the plurality of second louvers that are each adjacent to a corresponding portion of the additional plurality of flat heat transfer tubes. 
 
     
     
       5. The heat exchanger of  claim 4 , wherein the plurality of corrugated fins each further include a thermal resistor unit provided to a region between the plurality of flat heat transfer tubes and the additional plurality of flat head transfer tubes, the thermal resistor unit providing thermal insulation between the plurality of flat heat transfer tubes and the additional plurality of flat head transfer tubes. 
     
     
       6. The heat exchanger of  claim 5 , wherein the thermal resistor unit has a hole that extends through each of the plurality of corrugated fins, the hole of the thermal resistor unit having an opening area less than an opening area of the drain hole. 
     
     
       7. An air-conditioning apparatus, comprising:
 a heat source-side unit including a compressor, a flow switching device, and a heat source-side heat exchanger; and 
 a use-side unit including a use-side heat exchanger, 
 wherein the air-conditioning apparatus is configured to circulate refrigerant in such a manner that the refrigerant compressed by the compressor flows into the heat source-side heat exchanger or the use-side heat exchanger depending on a switching state of the flow switching device, and 
 wherein the heat source-side heat exchanger comprises the heat exchanger of  claim 1 . 
 
     
     
       8. The air-conditioning apparatus of  claim 7 , wherein the flow switching device is configured to switch in such a manner that
 when the refrigerant that passes through the heat source-side heat exchanger is to be evaporated, the refrigerant flows through the heat source-side heat exchanger to cause heat exchange between upstream portion of the refrigerant in a direction in which the refrigerant flows and downstream portion of air in a direction in which the air flows to pass through the heat source-side heat exchanger and heat exchange between downstream portion of the refrigerant in the direction in which the refrigerant flows and upstream portion of the air in the direction in which the air flows, and 
 when the refrigerant that passes through the heat source-side heat exchanger is to be condensed or when the heat source-side heat exchanger is to be defrosted, the refrigerant flows through the heat source-side heat exchanger to cause heat exchange between upstream portion of the refrigerant in the direction in which the refrigerant flows and upstream portion of the air in the direction in which the air flows and heat exchange between downstream portion of the refrigerant in the direction in which the refrigerant flows and downstream portion of the air in the direction in which the air flows.